Along with chilly temperatures winter brings a variety of bugs, often leaving us feeling run down or completely knocked over by colds and flu. Although there are no quick fixes to prevent colds and flu from striking, here are 8 simple steps you can take to ensure your immune system is functioning at peak performance.

1. Eat mostly whole and less-processed foods.

While there is no direct evidence that catching a cold or the flu is related to our diet, nutrition is essential for maintaining the body’s immune function. There are a variety of nutrients in food that can support the immune system and whole foods naturally contain plenty of these nutrients. For optimal health, the Heart Foundation recommends you eat plenty of vegetables and fruit, some whole grains in place of refined grains, legumes, nuts, seeds, and other sources of healthy fats such as oily fish. You may also choose to include non-processed lean meats, poultry and/or dairy.

2. Eat fruit and vegetables from a rainbow of different colours.

Did you know each different colour provides you with a different array of nutrients? That's right, so make sure you include plenty of green, red, purple/blue, yellow/orange and white/brown fruits and vegetables in your diet every day. Some examples of the immunity boosting nutrients found in fruit and vegetables includes:

Vitamin A (or carotenoids) iswhat gives fruits and vegetables their yellow/orange colour, so foods like pumpkin, carrots and kumara are naturally a rich source of this nutrient. However, you can also find vitamin A in some green foods, such as dark green leafy vege, because chlorophyll which makes them green, can mask the yellow/ orange colour. Milk and eggs are also good sources of vitamin A.

Vitamin C is not only found in citrus fruits, like oranges, but it also found in kiwifruit, capsicum, tomatoes, potatoes, berries and broccoli.

Phytonutrients are compounds found naturally in plants. Phenolics (found in most fruit and vegetables) and flavonoids (berries, onions, Brussels sprouts, citrus, kale and parsley) are common phytonutrients which are known to have immune benefits.

3. Choose mostly whole grains, with the grain still intact, rather than refined grains

While many of us only think about their superior fibre content when we think of whole grains (such as oats, barley, rye, quinoa, buckwheat and brown rice), they also contain many vitamins which can also help to support our immune system. These nutrients include:

Vitamin B6 - which is also found in vegetables and meat

Vitamin E - also found in nuts and vegetable oils

Zinc - also found in nuts, beans, dairy products, meat and shellfish

4. Make sure you're getting enough selenium

Unfortunately our New Zealand soils are low in this nutrient, meaning our fruit and vegetables are not good sources of selenium, unlike those grown in many other countries. Selenium is a mineral which helps to support the immune system. It is found in Brazil nuts and eating just two a day, will help you meet your daily selenium requirements.

5. Look after your gut

Did you know that ~70% of your immune system is localised in our gut? That’s why it’s super important to make sure that we look after the health of our gut. Having a diet rich in vegetables and fruit, and including whole grains for added fibre, will help to keep your gut functioning at its best. We can also look after our guts by feeding them with good bacteria (probiotics) to help restore the balance of healthly bacteria in the gut microbiome.

Probiotics are live bacteria which provide us (their host) with a proven health benefit. Examples of probiotics include Lactobacillus and Bifidobacterium. Probiotcs can be found in some fermented milk products, such as yoghurt, kefir, kombucha, kimchi, nato or sauerkraut. However, not all fermented foods contain probiotics and not all Lactobacillus or Bifidobacterium have probiotic activity.

6. Keep hydrated.

While not technically linked to supporting your immune function, your fluid intake can help to ease the symptoms of colds and flu - it prevents the throat and nose lining from drying out. Warm fluids are especially helpful as they can help moisten your throat and loosen mucus. Honey drinks (and add a dose of lemon for added vitamin C!) have been shown to ease coughing. Try to drink at least 8 glasses of fluid each day. This includes the water found in a glass of plain water, cups of tea/coffee, soups and other beverages.

7. Get enough sleep

For all the parents out of here, this can sometimes be a very tough ask as your sleep patterns are not your own. However, research shows that when we are well-rested our immune system benefits. When we are running on empty and in a sleep deficit, our immune system can suffer, leaving us more susceptible to picking up bugs.

8. Maintain good hygiene practices

Wash your hands regularly

Avoid close contact with those that are already sick

Keep surfaces clean

Follow good food safety practices

What about cold and flu home remedies?

There are some commonly talked about remedies for colds and flu but is there the science to back-up there claims?

Echinacea and colds

Echinacea is a herbal remedy often recommended to help alleviate the symptoms and defend against colds. However, there is still a great deal of conflicting evidence about its effectiveness and more research is required.

Garlic and colds

Garlic has been shown to help reduce the duration of colds and prevent their onset. Try to include garlic in cooking on a regular basis.

Should you feed a cold and starve a fever?

I’m sure you’ve all heard the old saying “Feed a cold, starve a fever”? This one happens to be supported by scientific evidence. However, it is likely to be more relevant for fevers caused by bacterial infections, as opposed to fevers caused by viral infections (the flu).